As known for many years, the average age of the world population has considerably risen. Motor disorders associated with aging suggest a future scenario wherein people with care needs in moving—especially walking and in activities connected with the fulfillment of their daily activities, even at home—will be more and more.
The robotic orthoses of the type also known as exoskeletons represent a promising solution to assist people—elderly and not—living with motor deficits. These orthosis have usually anthropomorphic form and are “worn” from the subject. For active assistance “purposes”, the orthosis can include a group of actuation which generates mechanical power and transfers it to the affected joint segment, frequently the user hip.
Several authors (A. B. Zoss, H. Kazerooni: “Biomechanical Design of the Berkeley Lower Extremity, Exoskeleton—BLEEX”; IEEE/ASME Transactions on Mechatronics, vol. 11, no. 2, April 2006) describe an exoskeleton equipped with a hydraulic actuator for generating the flexion-extension torque of the hip. This actuator is arranged laterally to the user's body, in correspondence of the femur. However, this positioning entails an increase in weight on the articular segment concerned, which has as a consequence an increase of the involved inertia. Moreover, the center of gravity of the whole structure is lower than the physiological one.
Also US 2011/166489 refers to an active hip orthosis, comprising a group of hydraulic actuation positioned posteriorly to the user's body.
The orthoses/exoskeletons of known type mentioned above have some drawbacks or unresolved needs.
First, the orthosis structure must be compatible with the degrees of freedom, the angular extensions and, in general, the kinematics of the body joints, including those not assisted.
Moreover, the orthosis must be able to adapt to the anthropometry of the subject and realize, on the whole, a human-robot comfortable and cinematically effective interface.
In addition, the above should be obtained with a limited mechanical complexity of the orthosis, also for the benefit of its reliability.
Finally, more critical aspects that could be optimized, also in relation to the other requirements set out above, are:                the position of the actuator elements with respect to the subject's body,        the mechanism of transmission of assistive action,        the aforementioned number and positioning of passive degrees of freedom,        the number and positioning of orthosis adaptation means to different users anthropometries (this feature is of particular importance when the same orthotic system is to be used by different subjects).        